/Engine/Source/Runtime/InteractiveToolsFramework/Public/BaseGizmos/GizmoMath.h
Find the intersection of the ray defined by RayOrigin and RayDirection with the cylinder defined by CylinderCenter, CylinderAxis, CylinderRadius, and CylinderHeight. Returns intersection success/failure in bOutIntersects and the hit depth parameter along the ray for the first intersection in OutHitDepth.
namespace GizmoMath { template<typename RealType> void GizmoMath::RayCylinderIntersection ( const FVector & CylinderCenter, const FVector & CylinderAxis, RealType CylinderRadius, RealType CylinderHeight, const FVector & RayOrigin, const FVector & RayDirection, bool & bIntersectsOut, RealType & OutHitDepth ) }